Study suggests increase in C-section births is preventing female evolution

A new study out of Vienna is suggesting the increase in women opting for cesarean section births is getting in the way of females evolving to have wider pelvises, which would accommodate the growing brains and heads of babies.

The study suggests that by sparing mothers with smaller pelvises and their babies from a natural vaginal birth, the genes for a narrower pelvis are surviving, resulting in more women who require C-sections. The findings are being met with some skepticism from those in the B.C. medical community.

“To say that in two or three generations we have changed, evolutionary, the size of a pelvis? I have a hard time accepting that,” said Dr. Ellen Giesbrecht of the B.C. Women’s Hospital.

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The number of babies being born by C-section around the world has been on the rise for some time. Thirty years ago in Canada, one in five expectant mothers underwent the procedure. That number has grown to one in three in B.C., with similar increases elsewhere.

Dr. Giesbrecht says the real rise in C-section births came with the introduction in the 1950s and ’60s of antibiotics to reduce infection, as well as anesthetics to make the process more bearable for the mother.

While the rates dropped somewhat in the 1970s, a decade later they were climbing again for a number of reasons, including women becoming pregnant at more advanced ages. Uncontrolled diabetes and obesity, which has also been on the rise, can result in bigger babies, which makes natural exits through an average pelvis nearly impossible.

Doctors are also suggesting that another reason for higher rates of C-sections is the increase of women opting to have repeat cesareans, simply because their first child was born that way.

“There’s a myth that says, ‘One a cesarean, always a cesarean,’ so women need to know that having a vaginal birth is a safe and healthy option,” said Dr. Sarah Munro of the University of British Columbia’s Department of Family Practice.

The study can be found at the Proceedings of the National Academy of Sciences journal website.

With files from Linda Aylesworth